1. Field of the Invention
The present invention relates to a transmission control device of a motorcycle, and in more particular to a transmission control device of a motorcycle in which a rider can perform a shift by a shift operation of a transmission without performing a clutch operation.
2. Description of the Related Art
In a motorcycle, when a shift operation is performed by a manual transmission, usually, a rider disconnects a clutch and subsequently performs an up-shift operation or down-shift operation, and lastly connects the clutch so that the shift operation is completed. Meanwhile, in a motorcycle for racing, there are cases in which the rider may perform an up-shift operation or down-shift operation without performing a clutch operation (hereinafter referred to as a “clutchless shift operation”) because a more prompt shift operation is required.
In a case of a clutchless shift operation, a shift operation is performed in a state in which torque is transmitted from an engine part to a drive-wheel part, or from a drive-wheel part to an engine part, so that it is difficult to disengage a mesh of gears. For this reason, the rider must adjust an engine's output to perform disengagement of the mesh of gears, and a mesh to next gears.
However, it is difficult for the rider to suitably perform such an output adjustment of the engine in various operating states. For this reason, when the rider performs a clutchless shift operation in a state in which an output adjustment of the engine is not suitable, there are cases in which smooth shifts cannot be performed.
Hence, as countermeasures to this, devices are developed in which an engine's output can be controlled according to a clutchless shift operation by the rider. For example, in a conventional technology disclosed in Japanese Patent Publication No. 5041974, the technology related to a clutchless shift operation is disclosed in that, in a shift operation of a transmission, a mesh of gears can be easily disengaged by reducing rotational force transmitted between an input shaft and an output shaft of the transmission.
In addition, in Japanese Patent Publication No. 4392794, a technology related to a clutchless shift operation is disclosed in which, by performing an open movement to a predetermined degree of opening on a throttle valve at a time of a down-shift operation, an engine's output after performing a mesh to next gears is smoothly changed, and shift shock produced at a time of the gear mesh is mitigated.